In order to produce a video with a perceived high level of image quality, it is essential that the scene elements of interest be in focus. Under carefully controlled video capture conditions, it is possible to take the time to properly compose and light the scene and to adjust the capture lens in a way to ensure the desired elements of the scene are in focus. Frequently, however, the capture conditions cannot be controlled in this manner, e.g., sports and wildlife videography. In this latter case, a well-known strategy is to capture the scene using multiple focus settings with the assumption that the video corresponding to one of the focus settings will have the desired scene elements in focus. One common approach is to use a camera with multiple capture lens and multiple image sensors, as in commonly-assigned U.S. Pat. No. 7,859,588 to Parulski et al. This approach has the disadvantage of doubling the number of expensive components in the camera (lens and sensor) and correspondingly increasing the size and complexity of the capture device. Another approach is to segment the optical field and image sensor into separate focus zones using an array of microlenses inserted into the optical path as in U.S. Patent Application 2010/0141802 to Knight et al. The disadvantage of this approach is the loss in the image resolution due to the segmentation of the image sensor. A third approach is to rapidly change the focus of the capture lens around the nominal focus position determined by the camera and to evaluate if a better focus position is achieved during the rapid focus change. If a better focus position is found, it becomes the new nominal focus position and the process is repeated until the focus position stabilizes, as in commonly-assigned U.S. Patent Application 2010/0091169 to Border et al. The disadvantage of this approach is that multiple focus position image information is not retained thereby preventing the ability to change the effective focus of the video after capture. Finally, in all these approaches, the depth of field of the resulting video is limited by the f-number and focal length of the capture lens and the camera to subject distance.
What is needed is a way to produce a video with all scene objects in focus regardless of camera lens settings or subject distances, using a camera with only one capture lens and one image sensor that permits the scene to be captured at the full resolution of the image sensor.